Inheritance, variation and evolution(seneca) Flashcards
][The two types of cell division are:
- Mitosis
- Meiosis
Mitosis is used in ———–reproduction.
asexual
Mitosis results in the …
formation of two genetically identical daughter cells.
Meiosis is used in ———- reproduction.
sexual
Meiosis results in the …
formation of four genetically non-identical daughter cells.
The process of reproduction where the nuclei of two gametes (sex cells) fuse to form a …
zygote (a process known as fertilisation)
There are four key features of sexual reproduction:
- Offspring are non-identical
- Cells divide by meiosis
- Male and female gametes fuse
- Two parents
————— are the gametes in animals.
Sperm and egg cells
Sperm and egg cells are the ——– in animals.
gametes
—————— contain the gametes in flowering plants.
Pollen and ovum cells
Pollen and ovum cells contain the ———– in flowering plants.
gametes
What is the name of the cell formed by the fusion of two gametes?
Zygote
Asexual reproduction is the process of reproduction that forms …
genetically identical offspring from only one parent.
Asexual reproduction is common in …
single-celled organisms and some plants.
There are four key features of asexual reproduction:
- No gamete fusion
- Offspring are clones
- Only one parent
- Cells divide by mitosis
The two sets of chromosomes are pulled to opposite ends of the cell. Then, the nucleus divides into …
two.
In sexual reproduction, male and female ——- fuse.
gametes
Gametes contain …
half of the number of chromosomes (containing DNA) found in all body cells.
Each cell has a pair of…
each chromosome (diploid cell).
During sexual reproduction, the male gamete will …
fertilise the female gamete and the fertilised cell now has the normal number of chromosomes (46 in humans).
Once the gametes have combined, the new cell divides by …
mitosis (the cell grows asexually).
As soon as the embryo reaches a certain size, cells begin to …
differentiate (specialise).
Division of cells by meiosis (or meiotic division) in reproductive organs produces gametes with …
half the number of chromosomes found in all other body cells.
Humans can speed up artificial selection through …
selective breeding of plants and animals.
Humans can speed up artificial selection through selective breeding of plants and animals.
This depends on …
genetic variation.
Humans can speed up artificial selection through selective breeding of plants and animals.
This depends on genetic variation.
This process has many benefits, including …
boosting food production and breeding fast horses.
Variation in the offspring increases the chances of a …
population being able to survive environmental change by natural selection.
Variation in the offspring increases the chances of a population being able to survive environmental change by natural selection.This is because …
some individuals are likely to be adapted to the new conditions.
If an organism can reproduce sexually or asexually, it often reproduces asexually when conditions are good. Advantages of asexual reproduction are:
- If conditions are favourable, producing lots of identical offspring is positive.
- Asexual reproduction is faster than sexual reproduction.
- No mate is required. Therefore, asexual reproduction is more efficient with regards to time and energy.
What are the 4 genetically different gametes produced during sexual reproduction called?
haploid cells
The genome is the entire (all) genetic material of an organism. Within a genome, there are lots of levels of organisation:
- DNA
- Genes
- Chromosomes
DNA is a …
double helix polymer, which means it is a polymer (a large molecule made up of many subunits) made up of two strands forming a twisted, ladder shape.
A gene is a —————–. Genes code for a sequence of amino acids, which combine to give a specific protein.
small section of DNA.
A gene is a small section of DNA. Genes code for a …
sequence of amino acids, which combine to give a specific protein
Long strands of DNA are coiled up to form ————-
chromosomes.
Chromosomes contain …
many genes.
Human body cells contain —pairs of chromosomes, one of each pair coming from each parent.
23
Human body cells contain 23 pairs of chromosomes, one of each pair coming from …
each parent.
A gene is a segment of DNA. There are about ——- genes in the smallest human chromosome.
300
The nucleus of eukaryotic cells contains chromosomes made of …
DNA molecules.
Each gene tells how a specific ——— should be made.
protein
In —- , the Human Genome Project was completed. Researchers had successfully studied the entire human genome.
2003
In 2003, the Human Genome Project was completed. Researchers had successfully …
studied the entire human genome.
In 2003, the ————————– was completed. Researchers had successfully studied the entire human genome.
Human Genome Project
In 2003, the Human Genome Project was completed. Researchers had successfully studied the entire human genome. Since then, extensive research has been carried out on it, resulting in a vast increase in our understanding. Potential future implications (effects) of this advance in knowledge include:
- Gene identification
- Human evolutionary and migratory history
- Improving understanding of inherited diseases
Identifying genes linked to different disorders, allowing those at risk to make …
informed lifestyle decisions based on the known risk factors.
DNA is a polymer made up of two long strands of small units that repeat throughout the structure, called …
nucleotides.
Each nucleotides is made up of …
a sugar, a phosphate and a base attached to the sugar.
The two long strands within each DNA molecule are held together by …
attractions between opposite bases.
Each base has one other specific base with which it pairs:
- T pairs with A.
- G pairs with C.
The sugar and phosphates of nucleotides form the …
long strands.
nucleotides are made up of:
- base
- phosphate
- sugar
You can remember the base pairs in DNA (T-A and G-C) by using the phrase …
Tigers Are Great Cats.
Each amino acid is coded for by ————————– (called a codon).
a specific sequence of three bases
Each amino acid is coded for by a specific sequence of three bases (called a ——- ).
codon
The order of the bases on the DNA tells us …
the order for combining amino acids to create particular proteins.
We can change the protein made by a gene by altering the …
sequence of bases in that gene.
The order of bases determines which amino acids are combined to create …
proteins.
The order of bases determines which ————- are combined to create proteins.
amino acids
The process of protein synthesis (creation) happens like this:
- Template taken
- Template used
- Delivery of amino acids
- Unique structure created
In the process of protein synthesis (creation), the template is used to guide protein synthesis on ribosomes located in …
the cytoplasm.
In the process of protein synthesis (creation), specific amino acids are delivered by —————— to the protein chain, where they are added in the order shown on the template.
carrier molecules
In the process of protein synthesis (creation), once complete, the long protein chain …
folds up, giving it a unique structure.
In the process of protein synthesis (creation), a template is taken from the…
DNA and leaves the nucleus.
In the process of protein synthesis (creation), specific amino acids are delivered by carrier molecules to the ———– , where they are added in the order shown on the template.
protein chain
In the process of protein synthesis (creation), specific amino acids are delivered by carrier molecules to the protein chain, where they are …
added in the order shown on the template.
In the process of protein synthesis (creation), once complete, the long protein chain folds up, giving it a unique structure.This unique structure is essential to the protein’s function, in the form of …
enzymes, hormones, or structural proteins (e.g. collagen).
If the order of bases on DNA changes, what happens to the proteins made using the DNA?
the amino acid sequence may change.
A mutation is a …
permanent change in the nucleotide sequence of DNA.
Mutations happen continuously and normally …
only slightly affect proteins or don’t affect them at all
Occasionally, a mutation may change the …
structure or shape of a protein.
—- genetic variants arise from mutations.
All
The outcome of a mutation is almost always detrimental to …
protein function.
The outcome of a mutation is almost always detrimental to protein function.
For example, in enzymes, the 1.
In structural proteins, their 2.
- substrate may no longer be able to bind to the active site.
- strength may be reduced.
Some regions of DNA do not encode …
protein sequences.
Some regions of DNA do not encode protein sequences.
The term given to these sections is …
non-coding DNA.
More rarely, a mutation may give a —————- , such as resistance to an antibiotic in bacteria.
survival advantage
More rarely, a mutation may give a survival advantage, such as resistance to an antibiotic in bacteria.
These mutations can be beneficial and represent the …
foundation of evolution by natural selection.
Alleles are …
different forms of the same gene.
Humans have pairs of every gene and in one gene, each half of the pair may have different …
alleles.
People’s characteristics are determined by the ——- that they have.
alleles
Alleles can either be …
dominant or recessive
A dominant allele is always …
expressed, regardless of the identity of the other allele.
A dominant allele is always expressed, regardless of the identity of the other allele.
It needs 1. to be expressed (2.).
- only one copy present
- BB or Bb
A dominant allele is represented by …
a capital letter, e.g. B.
A recessive allele is only expressed if …
the other allele is also recessive.
It is represented by …
a lowercase letter e.g. b. It needs two copies to be present to be expressed (bb).
Which kind of allele is always expressed?
A dominant allele
Genotype refers to the …
combination of alleles an organism has.
If the two alleles are different, we say that the person is …
heterozygous (Bb).
If the two alleles are the same, we say that the person is …
homozygous (BB or bb).
A phenotype is …
an observed characteristic of an individual.
The phenotype is determined by the …
interaction between the genotype and environment.
Earlobes being attached or free is an example of a ——- , where the alleles present will determine a characteristic, unless the environment interferes.
phenotype
Mutations happen continuously and in most cases, proteins are …
hardly affected, if at all.
Mutations happen continuously and in most cases, proteins are hardly affected, if at all. But occasionally, a mutation may change the —————- of a protein.
structure or shape
Monohybrid inheritance refers to the …
inheritance of traits determined by a single gene.
————————– refers to the inheritance of traits determined by a single gene.
Monohybrid inheritance
Punnett squares are diagrams that help us to …
visualise the outcome of a monohybrid cross.
Punnett Squares are used to calculate the …
ratio of offspring phenotypes.
People can develop disorders if they inherit …
certain alleles.
Cystic fibrosis is caused by a ——— allele.
recessive
Cystic fibrosis is a …
disorder of cell membranes.
Cystic fibrosis causes …
thick, sticky mucus to build-up in the lungs and digestive system.
We can use the knowledge that cystic fibrosis is caused by a recessive allele to work out …
the allele combinations of each individual in a family tree.
If a sufferer of cystic fibrosis has non-suffering parents, what are the parents?
heterozygotes
Polydactyly is a …
disorder where the sufferer has extra fingers or toes.
Polydactyly is caused by a ———– allele.
dominant
Polydactyly is a ————— disorder.
inherited
Family trees can be used to visualise the …
transmission of inherited disorders from one generation to the next.
Embryonic screening is a form of …
genome screening.
We can screen a person’s genome to …
look for genes that may make that person susceptible (vulnerable) to genetic disorders.
The advantages of embryonic screening are:
- IVF embryos
- Prevent suffering
- Financial saving
During IVF, most embryos are …
surplus to requirements anyway.
Although embryonic screening has advantages, it also has disadvantages:
- Discrimination
- Expensive
- Parents become selective
- Ethics
There is the potential that defining the desirability of an embryo based on their genetic make-up could promote …
discrimination.
Healthy human body cells contain 23 pairs of chromosomes, ——— of which is responsible for determining biological sex.
only one
This pair of chromosomes are called the sex chromosomes and can either be …
X or Y